SdhEG16 is part of a conserved RGxxE motif20; mutation of SdhEG16 in SdhAF2/SdhE/Sdh5 reduces covalent flavinylation of Complex II in bacteria20 and yeast5,10, and is associated with Complex II deficiency and paraganglioma in humans5. The gene discussed is SDHAF2; the disease is paraganglioma.